Method and composition for imparting water resistance to textile material



Patented Oct. 28, 1952 METHOD AND COMPOSITION FOR IMPART- ING WATERRESISTANCE 'ro TEXTILE MATERIAL Francis W. Minor, Arlington, Va., ArnoldM.- Sookne, Washington, D. 0., Milton Harris, Bethesda, Md., and Gray L.Pyle, Chicago, Ill., assignors, by mesne assignments, to the UnitedStates of America as represented by the Secretary of the Army NoDrawing. Application February 17, 1948, Serial No. 9,008

This invention is concerned with the production of water-resistantmaterials. More particularly, it relates to a treatment of a normallywater-nonresistant body, 6. g. a textile, with alower-alkyl-mono-substituted dichlorosilane or dibromosilane, wherebywater-resistance is coniferred upon such body.

It is known broadly to treat a glass, textile, or paper body with anorgano-silicon halide in the vapor or liquid phase to make itwater-repellent; see U. S. Patents No. 2,306,222, Patnode, and2,412,470, Norton, and British Patent No. 575,675, BritishThomson-Houston Company Limited.

The present invention is based on the discovery that certainlower-alkyl-monosubstituted dihalosilanes, particularly monomethyldichlorosilane, confer greater water-resistance on water-nonresistantbodies than any organo-silicon halides heretofore used for that purpose.For instance, a textile treated with a silanecontemplated by us, willabsorb considerably less water upon prolonged exposure to rain (e. g.for 1 hour) than any other organo-silicon halide of the prior art.

It is generally assumed that the organo-silicon halide, upon applicationto the body to be treated, hydrolyzes by reacting with atmosphericmoisture and/or with water previously absorbed in the body.

E, rns ixz 11120 RZSKOHM zHX B being an organic radical, Xa halogenatom, a: ranging from 1 to 3, y from to 2, and z from 1 to 3, the sum ofz+y+z in the monomer being 4 (the valence of silicon) The hydrolysisproduct then is assumed to condense in situ to form a thinwater-resistant silicone resin deposit upon the treated body:

non-injurious even to a delicate fabric body and,

4 Claims. (01. 117-161) contributeto high water-resistance values in thefinished product.

Thus it is a principal object of our invention to provide a durablywater-resistant body by treating-a normally water-nonresistant bodywitha lower-alkyl-monosubstituted dihalosilane.

Another principal object of our invention is a water-resistant textileadapted for military and civilian uses when made into clothing,,tentage,etc.

A further object of our invention is a novel organo-silicon halidetreatment of a normally water-nonresistant body in the presence of asubstance capable of controlling the acid formed during such treatment.

Still another object ofour invention is a method for rendering textileswater-resistant, which .method can be conveniently carried out inconventional textile treatment apparatus and which is readily taught tosemi-skilled or even unskilled personnel.

characteristics will not be appreciably impaired by repeated launderingor dry-cleaning.

Other objects and advantages of our invention-will appear-more fully inthe following description thereof.

We have found that'superior water-resistance properties are imparted toa normally waternonresistant body by immersing it in aloweralkyl-monosubstituted dichlorosilane or dibromosilane fil H I vAlkSiChofAlkSiBrz dissolved in an inert solvent, i. e. a solvent whichdoes not react with the silane. The alkyl substituent group may bemethyl, ethyl or propyl.

Monomethyldichlorosilane (CHsSiHCh) is a substance well adapted for thepurposes of our invention. Upon hydrolysis and subsequent condensationof the silane, the fabric or other body becomes water-resistant, whichphenomenon is believed by us to be due to the formation of a siliconeresin deposit having recurrent chloride, or liquid aliphatic or aromatichydrocarbons, such as a petroleum solvent (e. g. Varsol, a petroleumfraction boiling at about 150 0., made by Standard Oil Company) orbenzene.

The hydrochloric or hydrobromic acid formed during hydrolysis may beremoved by washing.

However, we prefer to neutralize it first by means of a weakly alkalinesubstance such as sodium bicarbonate or an alkali metal salt of a fattyacid, e. g. sodium acetate or potassium acetate. Strong alkalies areunsuitable where used on a body liable to be attacked thereby. Besidethe alkali metal salts of acetic acid, those of formic, propionic, andbutyric acid are suitable to control the hydrogen halide. Surprisinglywe have found further, that if the hydrolysis of the organo-slliconhalide is carried out in the presence of epoxybutene 61122011. CH CH;(3,4 epoxybutene-l) a highly water-resistant body results uponcondensation of. the silane, without strength loss from acid attack; weare at present unable to account for this surprising ability of theepoxybutene of controlling the mineral acid forming during hydrolysis.

Curing of the silane upon the body, which we believe to result in theformation of a silicone resin deposit, is efiected by drying at roomtemperature, preferably followed by exposure to an elevated temperature.We have obtained good curing efiects in the case of textiles by exposureto 105 C. to 150 C. for 15 minutes to 2 hours. The goods are washedpriorto the drying and/or heating step, in order to remove thehydrohalic acid which forms as the lay-product of the hydrolysis of theorgano-silicon halide as well as the substance used for controlling theacid. The body should be clean prior to commencement of the treatment,as dirt unfavorably influences the chemistry of the reaction; thus afabric should be thoroughly cleaned by washing or dry-cleaning prior totreatment.

Particularly favorable results are accomplished by treating a woolenfabric in accordance with our invention, as wool is an acid-resistantfiber; but cotton, paper and other bodies can be made water-resistantwith our method.

In evaluating water-resistance of the bodies treated in accordance withour invention, we have utilized the dynamic absorption test described inpar. 51) (1) of CCC-T-lsla Supplement, October 8, 1945, to FederalStandard Stock Catalog, section IV (part Supplement to FederalSpecification for Textiles; General Specifications, Test Methods. Thistest measures the interfiber liquid absorption of a textile bysimulating the effect of immersion in an agitated body of water, e. g. ariver, and consists of tumbling a test specimen in a tumble jar filledone-third with water at 55 R. P. M. for a designated time interval (say10, 20, 30 or 60 minutes), passing the specimen through a 60 lb. wringertwice (the first time without, and the second time between blotters),and weighing the specimen; the percentage of added-on weight of thespecimen is its dynamic absorption value. Naturally, the lower thedynamic absorption value, the more waterresistant the fabric.

By subjecting an untreated sample of 18 oz. wool serge to dynamicabsorption tests for various time intervals, we obtained the followingresults:

The following examples of water-resistance imparting treatments ofsamples of the same 18 oz. wool serge in accordance with our inventionwill illustrate various ways of practicing our invention and theadvantages obtained therefrom; however, we wish to be understood thatthe scope of our invention is not limited by any technical detailsrecited in such examples as, for instance, strength of silane solution,exact length of immersion, duration and temperature of ouring, etc.,inasmuch as such details will be readily varied by those skilled in theart without departing from the spirit of our invention and withoutsacrificing any of the advantages gained thereby.

Enumgclev 1 1 part by volume of monomethyl dichlorosilane is dissolvedin 30 parts by volume of carbon tetrachloride. A dry switch of serge isimmersed in this solution for 2 to 4 seconds, the carbon tetrachlorideis evaporated from the serge at room temperature, and the swatch 'isthen treated with a .2% solution of sodium carbonate to neutralizehydrochloric acid forming as a hydrolysis by-product. The swatch is nowwashed twice with water to remove the product of neuinalization and anyexcess of sodium carbonate solution, and finally baked for two hours atto C. The resulting product showed an increasein dry weight of 1.1% overthe untreated The fabric retains its water resistance even afterrepeated laundering:

DYNAMIC ABSORPTION VALUE PERCENT 10 Min.

23 Min. 30 Min. 60 Min.

After 5 launderings l9 24 27 Control tests substituting silanes of theprior art for waterproofing. textiles, gave the following dynamicabsorption values (prior to laundering) 10 Min. 20 Min. 30 Min. 00 Min.

Methyl tricblorosi1ane. 26. 5 34 34. 5 50 Diethyl dichlorosilanan. 37. 547 51 58. 5 Ethyl trichlorosilane 34 S9 44 47 Example 2 The treatment ofExample 1 was repeated by substituting a. solution of 1.5 part by volumeof monomethyl dichlorosilane in 100 parts of carbon tetrachloride.Dynamic absorption values of the treated swatch were as follows:

10 Min. 30 Min. 60 Min.

20 Min.

T Dynamic absorption values obtained from a 10 Min. 20 Min. so Min. 60Min.

25;. 9 so. i as. 2 43. 4

Example 3 A moist swatch of serge, containing 26% of water absorbedbetween its fibers, is briefly immersed in a solution of 1 part byvolume of monomethyl dichlorosilane in 40 parts by volume of carbontetrachloride. The solvent is evaporated in a fume hood, and thehydrochloric acid byproduct of the hydrolysis is removed by two washingsin a 2% solution of sodium acetate in water, followed by a 25 minuterinse in tap water, and baking for 2 hours at 110 C. The increase in dryweight is 0.9%, and dynamic absorption values in per cent as follows:

Min. 7 20 Min. 30 Min.

60 Min.

The treated fabric retains its water resistance after dry-cleaning, asshown by its dynamic absorption values after 1 hour's agitation in ahydrocarbon dry-cleaning fluid:

10 Min. 20 Min. 30 Min. 60 Min.

' It is believed that best results with moistened fabric are achieved byplacing it in equilibrium? with the atmosphere, 1. e. absorbing as much:

moisture as can be entirely absorbed within the fibers so that no liquidis sensibly present at the surface of the'fabric. Thus the higher thetemperature and relative humidity of the atmosphere, the more Water canbe held by th fabric without sweating.

Example 4 Dry swatches of serge were briefly immersed in a solution ofone part by volume of monomethyl -dichlorosilane in 25 parts by volumeof carbon tetrachloride. The solvent is evaporated in a fume hood, andthe hydrochloric acid byproduct of the hydrolysis is removed by a minuteimmersion in an aqueous solution of a weak base,

as indicated in the table below. This is followed by a two hour rinse inwater, a gentle squeezing out of excess water, and oven-curing for 2hours at l05-110 C. Dynamic absorption values in per cent were asfollows:

Thus, best water-resistance was accomplished by vusing sodiumbicarbonate and sodium acetate solutions, followed by sodium carbonateand ammonium hydroxide. Least favorable is neutraliz ation with sodiumhydroxide solution.

Example 5 Olive drab serge samples are pretreated by impregnation with awater solution of a salt of a weak acid, dried, and immersed in asolution of 1 part by volume of monomethyl dichlorosilane -in 25 partsby volume of carbon tetrachloride. I The solvent is evaporated and the(neutralized) hydrolysis byproducts removed by washing in water, and theswatches oven-dried at 105 to 110 C. for two hours. Dynamic absorptionvalues were as follows:

Impregnating Agent B2121? Sodium carbonate (15%) 1 29 39 45 52 Sodiumbicarbonate (23.5%) 1 19.5 25 29 36. 5 Sodium acetate (37%) l 16 20 22.5 I 30 Amount of salt deposited on swatch (percent per weight ofswatch); Best water resistance was achieved with the sodium acetateimpregnated swatches; free hydrochloric acid was absent, as could bedetermined from absence of discoloration.

Example 6 DYNAMIC ABSORPTION VALUE PERCENT i0 20 so to Tune Min. Min.Min. Min.

60min .18 21 23 27 min 1e 20 20 23 l5m1n l7 18 2O 23 2 months 17 18. 521. 5 2o. 5

Water resistance achieved by curing at to C. for 90 minutes, and bycuring at .150 C. for 15 minutes is thus substantially the same, andalmost as good as obtained by curing for two hours at 105 to 110 C. inaccordance with Example 4.

Example 7 to be free from hydrochloric acid and to have gained 7.2% ofweight; its dynamic absorption values were:

10 Min. 20 Min. so Min. 60 Min.

Example 8- Dry swatches of serge were treated with solutions ofmonomethyl dichlorosilane in various sample were (corresponding valuesof untreated poplin'samples inparenthesis) organic solvents (see tablebelow), the solvent 10 20 Mm 3o 60mm evaporated, the free hydrochloricacid (hydrolysis byproduct) neutralized with a sodium salt of a 27(45)30(45) 1 31%) 34(47) weak acid, rinsed, and oven-cured at 105-110 C. ior2:hours-. Dynamic absorption values were:

' r t I so so Swan 0 iii ft bg Min. Min. Min.

vol. of silane Skellysolye B (a petroleum fraction boiling at about 800., manuf. by ShelI-OilGo.) -m 20 24 26 2 Petroleum Ether (a mixture ofpentones and hexanes boiling between 40 0. an 7 o.) 25 2o 22 24. 31,Acetone; 33% 26 3 59 Ethen. 33 23 so 31 45 -Varso1(a petroleumfractionmanul'.

by Standard Oil Co.) boiling at about 150 o...- 33 14.5 18.5 21 21.5Benzene 16.5 18.0 1941 21.1 Moist Benzene. 40 16.2 17.8 18.8 218 Theforegoing table shows that aliphatic and Another sample of 5 oz. poplin.was immersed for aromatic hydrocarbon solvents for the silane. reseveralminutes in a solution composed of 1.8% sult in water resistance of thetreated fabric to monomethyl dichlorosilane, 2.4% -eD ybualmost the samedegree as carbon tetrachloride. tone-1, and 95.8% carbon tetrachloride(see Ex- Presence of a small amount of water in the solample 7). Thecarbon tetrachloride solution was vent is apparently non-injurious, asshown by 30 evap d y Suspension n a fu e hood for the resultsaccomplished with moist benzene. one hour, the sample was washed in awater The comparatively poor Water resistance with solution of sodiumacetate, rinsed for 30 minutes acetone or ether as the solvent indicatesthe in running p Water, and cured 90 i s inferiority of organic solventscontaining oxygen at 110 C. Dynamic absorption values were (corin themolecule for the purposes of water-resist- 35 espo di Va ues ofuntreated sample inp re ance imparting treatment in accordance with ourthesis) invention.

The followin examples show the results of water-resistance treatment inaccordance with. g m 20 60 our invention on fabrics other than 18 oz.serge: 4o 26 (46) 33 (48) 34 (48) 34 (48) Example 9 Various wool fabr cswere subj t d o a pr Breaking strength of the treated sample was8l%liminary dry cleaning with carbon tetrachloride of the untreated'sample.he s pl were e immer d briefly in a It will be seen from the foregoingdescription solution of 1 part by volume of monomethyl dithat by a waterresistance imparting treatment chlorosilane in 25 parts by Volume ofcarbon in accordance with the present invention, woolen tetrachloride. ehy or c d fo d as textiles and other normally water-nonresistant abyproduct of the resulting hydrolysis was nonbodies are converted intosuperior water resisttralized with a water solution of a sodium salt 50ant bodies. We are not able at this time to acof a weak acid, and theneutralization product count for the reason why the choice of a lowerwasrinsed out. The samples were finally cured alkyl-monosubstituteddichloro-or dibromosilane at 110 C. for about two hours. Dynamicabsorpresults in waterproofing superior to results action values of thetreated samples were as follows complished with fully substituted.halosilanes (corresponding dynamic absorption values of 'un- (that is,silanes wherein all four valences of the treated samples shown inparenthesis): silicon atom are satisfied by halogen and or- Fabric 10Min. 2'0 Min. 30'Min. Min.

Wovenfelt 32 (13a) 4015 (134.5) 43.5 (137.5) 49 (13c) TropicalWorsted..- 19 (51 21. 5 (55) 23 (51) 2e (51) 32 oz. Melton .l 7015 (135)I 68.50%) 93.5 (124 m3 134 Example 10 ganic substituents) however,theresults obtained 5 oz. poplin (a cotton fabric) was impregnated byour method clearly show that such is the case. with sodium acetate(CHaCOONaBI-IzO) from an We claim: aqueous solution so as to deposit 26%of sodium 1. A method of imparting water resistance to acetate perweight of sample. The sample was a normally water-non-resistant textilematerial,

immersed in a solution of monomethyl dichlorosilane, the solvent wasevaporated, the sample again immersed in an aqueous solution of sodiumacetate, rinsed, and cured for two hours at 130 comprising immersingsaid material into a solution in an inert solvent of alower-monoalkylsubstituted dihalosilaneselected. from the groupconsisting of monoalkyl dichlorosi-lane and mono- C. Dynamic absorptionvalues of the treated. alkyl dibromosilaneand having not more than threecarbon atoms in its alkyl substituent chain and 3,4-epoxybutene-1, inthe presence of moisture, whereby said substituted dihalosilane ishydrolyzed in situ and the hydrohalic acid formed as hydrolysisby-product is neutralized in situ, and exposing said material to anelevated temperature after its removal from said solution, whereby thehydrolyzed substituted silane is condensed in situ to a water resistantdeposit.

2. A composition for imparting water-resistance to a normallywater-non-resistant body, comprising a,lower-alkyl-monosubstituted-silane selected from the group consisting ofmonoalkyl dichlorosilane and monoalkyl dibromosilane, and having notmore than three carbon atoms in its alkyl substituent chain and3,4-epoxybutene-1 in an inert solvent.

3. A composition for imparting water-resistance to a normallywater-non-resistant body, comprising monomethyl dichlorosilane and 3,4-epoxybutene-l in an inert solvent.

4. A method of imparting water resistance to normallywater-non-resistant textile vmaterial, comprising immersing saidmaterial into a solution in an inert solvent of lower-monoalkylsubstituted dihalosilane selected from the group consisting of monoalkyldihalosilane and monoalkyl dibromosilane and having not more than 3carbon atoms in its alkyl substituent chain and 3,4-epoxybutene-1, inthe presence of moisture, whereby said substituted dihalosilane ishydrolyzed in situ and at least part of the hydrohalic acid formed ashydrolysis by-product is neutralized in situ, removing said material andthe hydrolyzed monoalkyl-substituted silane absorbed therein from saidsolution, expelling the solvent absorbed in said material, neutralizingthe remaining portion of the hydrohalic acid by-prodnot of thehydrolysis remaining in said material with sodium acetate, andcondensing the hydrolyzed substituted silane, which is absorbed by saidmaterial, in situ at an elevated temperature to a water-resistantdeposit.

FRANCIS W. MINOR. ARNOLD M. SOOKNE. MILTON HARRIS. GRAY L. PYLE.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS- Number Name Date 2,306,222 Patnode Dec. 22, 19422,386,259 Norton Oct. 9, 1945 2,412,470 Norton Dec. 10, 1946 2,449,572Welsh Sept. 21, 1948 2,469,625 Barry May 10, 1949 FOREIGN PATENTS NumberCountry Date 418,230 Great Britain Oct. 22, 1934 116,470 Australia Jan.19, 1943 OTHER REFERENCES Bennett, Concise Chemical 8: TechnicalDictionary, Chemical Publishing 00., 1947, pp. XX and 366.

1. A METHOD OF IMPARTING WATER RESISTANCE TO A NORMALLYWATER-NON-RESISTANT TEXTILE MATERIAL, COMPRISING IMMERSING SAID MATERIALINTO A SOLUTION IN AN INERT SOLVENT OF A LOWER-MONOALKYLSUBSTITUTEDDIHALOSILANE SELECTED FROM THE GROUP CONSISTING OF MONOALKYLDICHLOROSILANE AND MONOALKYL DIBROMOSILANE AND HAVING NOT MORE THANTHREE CARBON ATOMS IN ITS ALKYL SUBSTITUENT CHAIN AND 3,4-EPOXYBUTENE-1,IN THE PRESENCE OF MOISTURE, WHEREBY SAID SUBSTITUTED DIHALOSILANE ISHYDROLYZED IN SITU AND THE HYDROHALIC ACID FORMED AS HYDROLYSISBY-PRODUCT IS NEUTRALIZED IN SITU, AND EXPOSING SAID MATERIAL TO ANELEVATED TEMPERATURE AFTER ITS REMOVAL FROM SAID SOLUTION, WHEREBY THEHYDROLYZED SUBSTITUTED AILANE IS CONDENSED IN SITU TO A WATER RESISTANTDEPOSIT.